Carbon Filter by shubhamindia

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									Carbon Filter
1.What is Activated Carbon?



Carbon is an extremely porous material that attracts and holds a wide range of harmful contaminants.
Activated carbon is carbon which has a slight electro-positive charge added to it, making it even more
attractive to chemicals and impurities. As the water passes over the positively charged carbon surface,
the negative ions of the contaminants are drawn to the surface of the carbon granules.

Carbon is a substance that has a long history of being used to absorb impurities and is perhaps the
most powerful absorbent known to man. One pound of carbon contains a surface area of roughly 125
acres and can absorb literally thousands of different chemicals. Activated carbon is carbon which has a
slight electro-positive charge added to it, making it even more attractive to chemicals and impurities.
As the water passes over the positively charged carbon surface, the negative ions of the contaminants
are drawn to the surface of the carbon granules.

Activated carbon filters used for home water treatment typically contain either granular activated
carbon (GAC) or powdered block carbon. Although both are effective, carbon block filters generally
have a higher contaminant removal ratio. The two most important factors affecting the efficiency of
activated carbon filtration are the amount of carbon in the unit and the amount of time the
contaminant spends in contact with it. The more carbon the better. Similarly, the lower the flow rate
of the water, the more time that contaminants will be in contact with the carbon, and the more
absorption that will take place. Particle size also affects removal rates.

Activated carbon filters are usually rated by the size of the particles they are able to remove,
measured in microns, and generally range from 50 microns (least effective) down to 0.5 microns
(most effective).

A typical counter-top or under-the-counter filter system has from 12 to 24 ounces of activated carbon.
The most common carbon types used in water filtration are bituminous, wood, and coconut shell
carbons. While coconut shell carbon typically costs 20% more than the others, it is generally regarded
as the most effective of the three. All of our activated carbon filters use coconut shell carbon.

Activated carbon filters remove/reduce many volatile organic chemicals (VOC), pesticides and
herbicides, as well as chlorine, benzene, trihalomethane (THM) compounds, radon, solvents and
hundreds of other man-made chemicals found in tap water. Some activated carbon filters are
moderately effective at removing some, but not all, heavy metals. In addition, densely compacted
carbon block filters mechanically remove particles down to 0.5 micron, including Giardia and
Cryptosporidium, turbidity and particulates. Although some iron, manganese, and hydrogen sulfide will
be removed by these higher quality activated carbon filters, a manganese greensand iron reduction
filter is generally preferred to remove these contaminants as the effectiveness of carbon filter against
iron and manganese is generally short-lived if the contaminant concentration is high.

Carbon filters are NOT generally successful at removing dissolved inorganic contaminants or metals
such as minerals/salts (hardness or scale-causing contaminants), antimony, arsenic, asbestos,
barium, beryllium, cadmium, chromium, copper, fluoride, mercury, nickel, nitrates/nitrites, selenium,
sulfate, thallium, and certain radio nuclides. Removing these contaminants requires either a reverse
osmosis water filter system or a distiller (some can also be removed by KDF-55 or manganese
greensand).




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GAC does not remove sediment / particulate material very well, so they are often preceded by a
sediment filter. Sediment pre-filters also prolong the activate carbon cartridge life by eliminating gross
contaminants that would otherwise clog the activated carbon thereby reducing the surface area
available for absorption. Carbon block filters are generally better then GAC filters at removing
sediment.




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